hey, I DO THAT! you have to! it's ridiculous how long they make you wait sometimes and i don't have time to hold a phone to my ear.
i use an earpiece when i'm calling vendors, but i still use speaker on hold cuz i don't want that crappy elevator music playing in my ear. all "on hold" music should be slayer. always.
but i have my own office and i turn the volume way down while i wait, so this post doesn't really count.